1. These are random samples of Korean SAT score of students who enrolled in business statistics class. Construct 95% confidence interval for average SAT score of the students 330 350 365 387 340 325 344 360 335 322 378 380 377 368 358 370 2. The manager of CORAIL introduces new traffic management system. The manager expected that the new system makes the arrival time of the metro more constant. So, she sampled the metro's interarrivals times of Suwon station randomly. 8 8.9 8.2 8.5 7.7 7.5 6.9 8.4 7.2 8.2 7 8.6 9 8.7 6.5 6.9 a. If the variance of the interarrival time for the old system was 1 min, can the manager say that, new system is superior to old system? (a =0.05) b. What is the confidence interval for the variance of the interarrival time base on the data?